Open fields edged by trees have always been favorite places of mine. And this Tuesday,in the fields on either side of the park, Monarch butterflies were everywhere! Bear Creek may be hosting fall migrators on their way to Mexico – or we’ve just had a big hatch of these beautiful and ecologically fragile creatures. In fact, many butterflies, bees and darners fluttered, hummed and hovered over the swaying seas of gold in Bear Creek, while grasshoppers serenaded them beneath the tall stems.
Some speculate that humans love open fields because our ancient ancestors felt safe where they could see into the distance but escape into the trees. I just know I’m very happy in a field full of wildflowers.
First, of course: The Monarchs and the Hummer!
After only seeing the occasional Monarch Butterfly (Danaus plexippus) this summer, on Tuesday they were floating and fluttering all over the park! Though the Joe Pye (Eutrochium maculatum) in the Eastern Old field seems to be past its peak, its nectar drew in a Monarch (and other butterflies below) anyway.
I considered myself lucky to get so close – but when I started down the Western Sloping Path from north to south, wow! Monarchs surrounded me every step of the way. I believe I saw at least a dozen there, but I’ll share just a few who were enjoying the New England Asters.
At the very bottom of the sloping path, I watched as two Monarchs approached and fed on the same plant.
Just at that special moment, I saw the second Ruby-Throated Hummingbird (Archilochus colubris) I’ve ever seen at Bear Creek – a female, hovering momentarily as she looked at me and then zoomed off toward the woods. No photo, of course, but perhaps this silhouette of a hummer in mid-hover from a few years ago will help you visualize the one I saw this week.
Fields Full of Wildflowers and their Beautiful Visitors
Eastern Tiger Swallowtails (Papilio glaucus) fluttered quickly across the golden fields. I just caught sight of one in the far distance on the Eastern Path on Sunday so here’s a picture from another August, when a male landed on Spotted Knapweed, an invasive wildflower.
New England Asters (Symphyotrichum novae-angliae) increasingly complement the Goldenrods’ glow as these vivid native flowers grow tall to reach their share of the thinning sunlight.
A Great Spangled Fritillary in the Eastern field paused on fading blossoms of Joe Pye to take a sip, just like the Monarch did.
And the Silver-spotted Skipper (Epargyreus clarus) rested beneath a blossom of the same plant.
About That Hum in the Old Fields…
Honey Bees (Apis mellifera), native Bumblebees (genus Bombus) and even Eastern Yellow Jacket Wasps (Vespula maculifrons ) hum among the flowers in the Old Fields. Don’t worry; they’re much too busy gathering pollen, or in the case of wasps, eating nectar, to bother with us humans.
Always on the lookout for a quick munch, the big Canada Darner Dragonfly (Aeshna canadensis) zooms and dives over the blossoms below. This B-52 of insects consumes a lot of late summer bugs.
Below the Darner, a modest wet-footed flower stands among the wetland reeds in the Eastern Old Field. According to Wikipedia, Boneset (Eupatorium perfoliatum) got its name because our ancestors believed that since the leaves clasped the stem “wrapping the leaves in bandages around splints would help mend broken bones.”
Down in the grass, the Red-legged Grasshoppers (Melanoplus femurrubrum) sing lustily as a backdrop to all this beauty by rubbing their rasp-like back leg against their forewing.
A Bumblebee buzzed softly as it balanced carefully at the top of a stem of Canada Goldenrod
Yellow Jackets, like all wasps, don’t do much pollinating because they lack the fuzzy body hair of bees. They generally eat nectar but collect bugs for the protein they feed to their young.
What’s That Bump on the Goldenrod, Anyway?
As you’re wandering through the Old Fields, you may have noticed some strange shapes on the stalks and tips of Canada Goldenrod (Solidago canadensis). Galls are growths on plant stems caused by insects who lay their eggs on the plants in the spring. When the larva hatch, they eat into the plant, causing it to form a gall around them. Inside, the larva eats until late summer when it forms a pupa which spends the winter inside that protective covering. In spring, the adult insect emerges to restart the life cycle. Galls don’t kill the Goldenrod; they just look funny!
The ball gall is the most common goldenrod gall and is formed by the small Goldenrod Gall Fly (Eurosta solidaginis). With its hard surface, this gall seems like a decent place to spend the winter, doesn’t it? During the summer, though, some wasps lay eggs in galls and their larvae hatch and make a meal of the gall fly’s. And in the winter, Downy Woodpeckers drill holes in galls to reach the pupae, and Gray Squirrels chew on galls to do the same. Obviously enough Gall Flies survive in these dwellings to start a new crop next spring, so nature stays in balance. I think this gall may have been invaded by a wasp.
Goldenrods also harbor the very tiny (.2″) Goldenrod Gall Midge (Rhopalomyia solidaginis) which causes a rosette gall. Once the grub of this tiny creature hatches, the stem of the goldenrod generally stops growing but keeps producing leaves which bunch up and make a nice hiding place for a midge’s larva to grow – along with spiders and other midges who may move in. Sometimes, as in this photo, the stem will continue to grow above the rosette gall, but it’s much more spindly.
For years I saw willows in the park that seemed to be producing pine cones at the end of their branches. Turns out they’re Willow Pine Cone Galls, made by a tiny (about .2″) midge scientifically known as Rhabdophaga strobiloides. The pine cone-shaped gall that its larva causes can harbor many species. According to the University of Wisconscin-Milwaukee’s Field Station website, “Beetles, caterpillars, sawflies, cynipid wasps, midges, and the eggs of meadow grasshoppers have been found inside pine cone galls.” They’re now on a willow on the west side of the Center Pond and can also be seen in the wetland area east of the Eastern Path.
The Eastern Old Field rolls down to the Center Pond and the Western one slopes dramatically to the west. The trails that wind across them are full of strange and beautiful creatures and the plants that feed on and live in them. Walk quietly. Look closely. Listen carefully. And when nature shares a secret with you, please share it with the rest of us.
*Footnote: My sources for information, as well as Oakland Township Stewardship Manager Dr. Ben VanderWeide, are as follows: Ritland, D. B., & Brower, L. P. (1991). The viceroy butterfly is not a Batesian mimic; Stokes Nature Guides: A Guide to Bird Behavior Volumes 1-3, Allaboutbirds.org, the website of the Cornell Ornithology Lab at Cornell University; Wikipedia; http://www.butterfliesandmoths.org; Herbarium of the University of Michigan at michiganflora.net.; various Michigan Field Guides by Stan Tekiela; Butterflies of Michigan Field Guide by Jaret C. Daniels; University of Wisconsin's Bug Lady at www4.uwm.edu/fieldstation/naturalhistory/bugoftheweek/ for beetle info http://www.migrationresearch.org/mbo/id/rbgr.html for migration info, and invaluable wildflower identification from local expert, Maryann Whitman.